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Date: Fri, 3 Feb 2006 10:23:09 -0600 (CST)
From: Dave Bodenstab <dave AT bodenstab DOT org>
Message-Id: <200602031623.k13GN9mF029768@base686.home.org>
To: cygwin AT cygwin DOT com
Subject: Re: Possible bug with mmap on XP?
In-Reply-To: <20060203085727.GY15572@calimero.vinschen.de>
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On Thu Feb  2 22:55:08 2006 Corinna Vinschen <corinna-cygwin AT cygwin DOT com> wrote:

> > 
> > Is this the way things are supposed to work on XP?
>
> This is a constraint of the underlying OS, yes.  The old implementation
> of mmap used up to 1.5.18 didn't support PROT_EXEC at all, it was just
> fake.  Since 1.5.19, PROT_EXEC mapping is now supported correctly, which
> means, the underlying NT functions are called requesting PAGE_EXECUTE
> protection.
>
> But here's the problem.  To create file mappings with PAGE_EXECUTE
> protection, the file must be opened with GENERIC_EXECUTE access. 
> This is done internally in mmap, but it fails if the file doesn't
> have the execute permission set.
>
> Whether or not this behaviour is backed by SUSv3, I'm not sure.  SUSv3
> states "if an implementation cannot support the combination of access
> types specified by prot, the call to mmap() shall fail.", so here's one
> situation in which the implementation can't support the combination of
> access types specified by prot.

OK.

I would like to modify my program to set the required permissions.
Is the mapping between Cygwin's uname()'s sysname and XP, NT, 98SE,
98, etc. available somewhere?  Actually, if I could just tell if the
underlying windows is XP, that would be sufficient I think.  

Thanks.



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